<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>document</title>
    <style>
        #main_body{
            overflow:hidden;
        }
        #zuo{
            float: left;
        }
        #you{
            float: left;
        }
        .city{
            list-style-type: none;
            width: 80px;
            text-align: center;
            font-size: 22px;
            line-height: 1.6;
            padding: 0px 0px;
            margin: 0px 0px;
        }
        .area{
            list-style-type: none;
            width: 50px;
            text-align: center;
            font-size: 14px;
            line-height: 1.6;
            color: aliceblue;
            padding: 0px 0px;
            margin: 0px 0px;
            position: absolute;
            left: 95px;
            top: 23px;
            display: none;
        }
        .city > li{
            background-color: darksalmon;
            border-bottom: 1px solid white;
        }
        .area > li{
            background-color: cadetblue;
            border-bottom: 1px solid white;
        }
    </style>
    <script src="https://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js"></script>
    <script>
        $(function(){
            $('#yi').mouseenter(function(){
                $('#yc').fadeIn('fast').animate({width:'55px'},'fast');
            });
            $('#yi').mouseleave(function(){
                $('#yc').animate({width:'50px'}).fadeOut();
            });

            $('#jin').mouseenter(function(){
                $('#jz').fadeIn('fast').animate({width:'55px'},'fast');
            });
            $('#jin').mouseleave(function(){
                $('#jz').animate({width:'50px'}).fadeOut();
            });

            $('#xiao').mouseenter(function(){
                $('#xg').fadeIn('fast').animate({width:'55px'},'fast');
            });
            $('#xiao').mouseleave(function(){
                $('#xg').animate({width:'50px'}).fadeOut();
            });

            $('#xian').mouseenter(function(){
                $('#xn').fadeIn('fast').animate({width:'55px'},'fast');
            });
            $('#xian').mouseleave(function(){
                $('#xn').animate({width:'50px'}).fadeOut();
            });

        })
        // window.onload = function() {
        //     document.getElementById('yi').onmouseenter = function(){
        //         let elm = document.getElementById('yc');
        //         elm.style.display = 'inline';
        //     }
        //     document.getElementById('yi').onmouseout = function(){
        //         let elm = document.getElementById('yc');
        //         elm.style.display = 'none';
        //     }
        //     document.getElementById('jin').onmouseenter = function(){
        //         let elm = document.getElementById('jz');
        //         elm.style.display = 'inline';
        //     }
        //     document.getElementById('jin').onmouseout = function(){
        //         let elm = document.getElementById('jz');
        //         elm.style.display = 'none';
        //     }
        //     document.getElementById('xiao').onmouseenter = function(){
        //         let elm = document.getElementById('xg');
        //         elm.style.display = 'inline';
        //     }
        //     document.getElementById('xiao').onmouseout = function(){
        //         let elm = document.getElementById('xg');
        //         elm.style.display = 'none';
        //     }
        //     document.getElementById('xian').onmouseenter = function(){
        //         let elm = document.getElementById('xn');
        //         elm.style.display = 'inline';
        //     }
        //     document.getElementById('xian').onmouseout = function(){
        //         let elm = document.getElementById('xn');
        //         elm.style.display = 'none';
        //     }
        // }
        
    </script>
</head>
<body>
    <div id="main_body">
        <div id="zuo">
            <ul class="city">
                <li id="jin">荆州</li>
                <li id="yi">宜昌</li>
                <li id="xiao">孝感</li>
                <li id="xian">咸宁</li>
            </ul>
        </div>
        <div id="you">
            <ul id="yc" class="area">
                <li>当阳</li>
                <li>长阳</li>
                <li>枝江</li>
                <li>宜都</li>
                <li>秭归</li>
            </ul>
            <ul id="jz" class="area">
                <li>area a</li>
                <li>area b</li>
                <li>area c</li>
                <li>area d</li>
                <li>area e</li>
            </ul>
            <ul id="xg" class="area">
                <li>area A</li>
                <li>area B</li>
                <li>area C</li>
                <li>area D</li>
                <li>area E</li>
            </ul>
            <ul id="xn" class="area">
                <li>area 1</li>
                <li>area 2</li>
                <li>area 3</li>
                <li>area 4</li>
                <li>area 5</li>
            </ul>
        </div>
    </div>
    
</body>
</html>